The 3rd Generation Partnership Project (3GPP) standards organization defines the specifications for mobile telecommunications network (3GPP network), which is a most commonly applied wide-area mobile telecommunications network. As an easy-to-access, high-speed and low-cost local area communications network, a wireless local area network (WLAN) is also widely deployed and used. A user can access the 3GPP network or the WLAN by using a user equipment (UE) to perform voice services, data services, multimedia services, and so on, for example, the user can access the Internet, or perform a voice or a video call.
In consideration of network traffic control and flexibility of implementing services by the UE, the industry currently discusses supporting a UE to access a 3GPP core network through a 3GPP access network and access the 3GPP core network through a non-3GPP access network (such as the WLAN), and further to access the Internet through the 3GPP core network, thereby implementing interworking between the 3GPP network and the non-3GPP access network (such as the WLAN), so that the 3GPP network offloads data to the non-3GPP access network, and uniform charging, quality of service (QoS) control, and the like are performed. The industry further discusses how to support a UE to perform communication using WLAN access and 3GPP access simultaneously, to transmit an Internet Protocol-based service flow, namely, an Internet Protocol (IP) flow, and implement seamless switching of the IP flow between the WLAN access network and the 3GPP access network. For example, at a certain moment, the UE performs voice over IP (VoIP) by using the 3GPP access network, and transmits a video stream or downloads data by using the WLAN access network; later, due to a change of a network condition, a carrier policy, or user preference, the UE moves, to the 3GPP access network, the data service transmitted in the WLAN access network. Such a feature is known as an IP flow mobility feature.
Then, in a solution to supporting the IP flow mobility under discussion in the industry, a UE is required to support, for example, dual stack mobile IP version 6 (DSMIPv6), but most existing UEs do not support the DSMIPv6 protocol (due to the cost, technology, or other factors). Consequently, it is difficult to implement this DSMIPv6-based IP flow mobility solution in the existing communications network.